Intermittence of blood flow in liver sinusoids, studied by high-resolution in vivo microscopy

1995 ◽  
Vol 269 (5) ◽  
pp. G692-G698 ◽  
Author(s):  
P. J. MacPhee ◽  
E. E. Schmidt ◽  
A. C. Groom
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Liver Sinusoids ◽  
Video Recordings ◽  
Red Blood Cell Velocity ◽  
The Mean ◽  
Flow Stasis ◽  
Fast Flow

Kupffer cell migration and leukocyte-vessel wall interactions cause temporary slowing and/or stoppage of blood flow through individual liver sinusoids. Such temporal heterogeneity of flow was quantified in anesthetized mice and rats. Video recordings of red blood cell flow in 44 networks containing 8-16 sinusoids each were analyzed for 5- to 10-min periods. Flow was graded "fast," "slow," "stopped," or "reversed" based on red blood cell velocity. The mean numbers of flow changes (between grades) per minute in zone 1 vs. zone 3 were 1.39 vs. 0.78 (mouse) and 1.25 vs. 0.09 (rat). The mean percentage of time for each flow grade differed significantly between zones 1 and 3 and between species. For example, fast flow was present in zone 1 sinusoids for 51% of the time in mice and for 74% in rats; in zone 3 the corresponding numbers were 76 and 95%. Flow stasis was present in zone 1 sinusoids for 19% of the time in mice and for 7% in rats; in zone 3 the corresponding numbers were 2 and 0%. Thus considerable intermittence of perfusion exists, and the flow conditions create very different microenvironments for hepatocytes in zone 1 vs. zone 3.

In vivo microvascular structural and functional consequences of muscle length changes

1997 ◽  
Vol 272 (5) ◽  
pp. H2107-H2114 ◽  
Author(s):  
D. C. Poole ◽  
T. I. Musch ◽  
C. A. Kindig
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Oxygen Delivery ◽  
Sarcomere Length ◽  
Flow Dynamics ◽  
Capillary Diameter ◽  
Luminal Diameter ◽  
Length Changes

As muscles are stretched, blood flow and oxygen delivery are compromised, and consequently muscle function is impaired. We tested the hypothesis that the structural microvascular sequellae associated with muscle extension in vivo would impair capillary red blood cell hemodynamics. We developed an intravital spinotrapezius preparation that facilitated direct on-line measurement and alteration of sarcomere length simultaneously with determination of capillary geometry and red blood cell flow dynamics. The range of spinotrapezius sarcomere lengths achievable in vivo was 2.17 +/- 0.05 to 3.13 +/- 0.11 microns. Capillary tortuosity decreased systematically with increases of sarcomere length up to 2.6 microns, at which point most capillaries appeared to be highly oriented along the fiber longitudinal axis. Further increases in sarcomere length above this value reduced mean capillary diameter from 5.61 +/- 0.03 microns at 2.4-2.6 microns sarcomere length to 4.12 +/- 0.05 microns at 3.2-3.4 microns sarcomere length. Over the range of physiological sarcomere lengths, bulk blood flow (radioactive microspheres) decreased approximately 40% from 24.3 +/- 7.5 to 14.5 +/- 4.6 ml.100 g-1.min-1. The proportion of continuously perfused capillaries, i.e., those with continuous flow throughout the 60-s observation period, decreased from 95.9 +/- 0.6% at the shortest sarcomere lengths to 56.5 +/- 0.7% at the longest sarcomere lengths and was correlated significantly with the reduced capillary diameter (r = 0.711, P < 0.01; n = 18). We conclude that alterations in capillary geometry and luminal diameter consequent to increased muscle sarcomere length are associated with a reduction in mean capillary red blood cell velocity and a greater proportion of capillaries in which red blood cell flow is stopped or intermittent. Thus not only does muscle stretching reduce bulk blood (and oxygen) delivery, it also alters capillary red blood cell flow dynamics, which may further impair blood-tissue oxygen exchange.

scholarly journals Comparison of OPS imaging and conventional capillary microscopy to study the human microcirculation

2001 ◽  
Vol 91 (1) ◽  
pp. 74-78 ◽  
Author(s):  
Keshen R. Mathura ◽  
Karlijn C. Vollebregt ◽  
Kees Boer ◽  
Jurgen C. De Graaff ◽  
Dirk T. Ubbink ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Venous Occlusion ◽  
Orthogonal Polarization ◽  
Capillary Microscopy ◽  
Cell Velocity ◽  
Orthogonal Polarization Spectral ◽  
Red Blood Cell Velocity ◽  
Ops Imaging

Orthogonal polarization spectral (OPS) imaging is a new clinical technique for observation of the microcirculation of organ surfaces. For validation purposes, we compared OPS images of the nailfold skin with those obtained from conventional capillary microscopy at rest and during venous occlusion in 10 male volunteers. These images were computer analyzed to provide red blood cell velocity and capillary diameters of the same nailfold capillaries at rest and during venous occlusion. Results showed that OPS images provided similar values for red blood cell velocity and capillary diameter as those obtained from capillary microscopy images. OPS imaging, however, provided significantly better image quality, as shown by comparison of image contrast between OPS imaging and capillary microscopy. This made image analysis better and easier to perform. It is anticipated, therefore, that OPS imaging will become a new and powerful technique in the study of the human microcirculation in vivo because it can be used on human internal organs.

In Vivo Rat Closed Spinal Window for Spinal Microcirculation: Observation of Pial Vessels, Leukocyte Adhesion, and Red Blood Cell Velocity

Neurosurgery ◽  
1999 ◽  
Vol 44 (1) ◽  
pp. 156-161 ◽  
Author(s):  
Mami Ishikawa ◽  
Eiichi Sekizuka ◽  
Shuzo Sato ◽  
Noriyuki Yamaguchi ◽  
Katsuyoshi Shimizu ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Leukocyte Adhesion ◽  
Pial Vessels ◽  
Cell Velocity ◽  
Red Blood Cell Velocity

Capillary blood flow and tissue metabolism in skeletal muscle during sympathetic trunk stimulation

1998 ◽  
Vol 274 (2) ◽  
pp. H430-H440 ◽  
Author(s):  
Miklós Pál ◽  
András Tóth ◽  
Peipei Ping ◽  
Paul C. Johnson
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Sympathetic Trunk ◽  
Sartorius Muscle ◽  
Sympathetic Stimulation ◽  
Flow Reduction ◽  
Cell Velocity ◽  
Nadh Fluorescence ◽  
Red Blood Cell Velocity

NADH fluorescence at tissue sites 15–20 μm in diameter and red blood cell velocity in adjacent capillaries were measured in resting sartorius muscle of the anesthetized cat during a 3-min period of sympathetic trunk stimulation. At stimulation frequencies of 2 and 4 Hz, red blood cell velocity fell briefly to 30–40% of control and then returned to ∼75% of control values (vascular escape). No change in NADH fluorescence was observed. With stimulus frequencies of 6–12 Hz, flow reduction was greater and led to an increase in fluorescence when the flow reduction was >50% and was sustained for >30 s. NADH changes were more pronounced at tissue sites near venous capillaries than at sites near arterial capillaries. Hyperemia ensued after the end of sympathetic stimulation only when NADH fluorescence rose during stimulation. Resting blood flow in this muscle appears to be well above the minimum required to support oxidative metabolism. A shift to anaerobic metabolism does not appear to cause vascular escape during sympathetic stimulation but appears to be required for poststimulation hyperemia. These observations suggest that two separate oxygen-dependent mechanisms elicit vasodilation during and after sympathetic trunk stimulation.

Distribution of microvascular pressure in arteriolar vessel trees of ventilated rabbit lungs

1993 ◽  
Vol 265 (5) ◽  
pp. H1510-H1515 ◽  
Author(s):  
G. E. Kuhnle ◽  
A. R. Pries ◽  
A. E. Goetz
Keyword(s):  
Blood Flow ◽  
Pressure Drop ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Thoracic Wall ◽  
Segment Length ◽  
Rabbit Lung ◽  
Main Trunk ◽  
Cell Velocity ◽  
Red Blood Cell Velocity

We have developed a new in vivo microscopic technique for comprehensive measurements of vessel diameter, segment length, and red blood cell velocity in discrete arteriolar vessel trees of the lung. In anesthetized and mechanically ventilated rabbits, a transparent window was implanted into the right thoracic wall. We injected fluorescently labeled red cells to visualize blood flow and to measure red blood cell velocity. The distribution of microvascular pressures was simulated in a computer model based on morphometric and microhemodynamic data. Of the total pulmonary vascular pressure drop from pulmonary artery to left atrium, on average 2.5% occurred in distal arteriolar vessel trees with main trunk diameters of 73-111 microns. Along the pathlength from main trunk to terminal arterioles (0.18-2.79 mm), the pressure drop ranged between 0.06 and 0.94 mmHg. The pressure drop along individual pathways correlated significantly with pathlength of terminal arterioles, whereas red blood cell velocity did not. The results indicate that in terminal arteriolar vessel trees of the ventilated rabbit lung the resistance to blood flow is low, and the heterogeneity of microvascular pressures in arterioles feeding capillary networks is high.

scholarly journals The endothelial glycocalyx promotes homogenous blood flow distribution within the microvasculature

2016 ◽  
Vol 311 (1) ◽  
pp. H168-H176 ◽  
Author(s):  
P. Mason McClatchey ◽  
Michal Schafer ◽  
Kendall S. Hunter ◽  
Jane E. B. Reusch
Keyword(s):  
Blood Flow ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Vessel Wall ◽  
Tissue Perfusion ◽  
Cell Interactions ◽  
Microvascular Perfusion ◽  
Endothelial Glycocalyx ◽  
Heterogeneous Distribution

Many common diseases involve impaired tissue perfusion, and heterogeneous distribution of blood flow in the microvasculature contributes to this pathology. The physiological mechanisms regulating homogeneity/heterogeneity of microvascular perfusion are presently unknown. Using established empirical formulations for blood viscosity modeling in vivo (blood vessels) and in vitro (glass tubes), we showed that the in vivo formulation predicts more homogenous perfusion of microvascular networks at the arteriolar and capillary levels. Next, we showed that the more homogeneous blood flow under simulated in vivo conditions can be explained by changes in red blood cell interactions with the vessel wall. Finally, we demonstrated that the presence of a space-filling, semipermeable layer (such as the endothelial glycocalyx) at the vessel wall can account for the changes of red blood cell interactions with the vessel wall that promote homogenous microvascular perfusion. Collectively, our results indicate that the mechanical properties of the endothelial glycocalyx promote homogeneous microvascular perfusion. Preservation or restoration of normal glycocalyx properties may be a viable strategy for improving tissue perfusion in a variety of diseases.

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